Valve for rock drills



Patented Sept. 3, 1940 UNITED STATES amaze PATENT OFFICE VALVE FOR ROCK DRILLS Application January 13, 1939, Serial No. 250,777

2 Claims.

This invention relates broadly to rock drills, but more particularly to a valve construction for fluid actuated rock drills of the percussive type.

One object of this invention is to provide a valve readily responsive to the action of the motive fluid.

Another object of this invention is to produce an improved rock drill valve forming a simple assembly which is strong, durable and eflicient.

Other objects of this invention will be apparent from the following detailed description wherein similar characters of reference designate corresponding parts and wherein:

Fig. 1 is an elevational sectional view of a rock drill embodying the invention. 7

Fig. 2 is a iragmental View similar to Fig. 1 illustrating the valve in another position.

Fig. 3 is a cross sectional View taken in a plane indicated by line 33 in Fig. 1.

Fig. 4 is a cross sectional view taken in a plane indicated by line l-- l in Fig. 1.

Fig. 5 is a cross sectional view taken in a plane indicated by line 55 in Fig. 1.

Referring to the drawing, 9 represents a cylin- 25 der formed with a piston chamber l0 having a piston I I reciprocable therein and formed with a stem I2 capable of delivering impacts to a drill steel (not shown), which stem is slidable through a spacer l3 held stationary within the front end of the piston chamber l9. Intermediate its ends, the cylinder 9 is provided with the usual exhaust grooves 14 opening into a common exhaust port 15. The upper end of the cylinder 9 is counterbored as at Hi to accommodate a valve cap IT, a valve casing 18, and a valve bushing I9, which form together a valve housing having a valve 26 slidable therein. Above the valve bushing l9, there is also mounted in the counterbore E6, the ratchet ring 2! of a rotation mechanism which includes the head 22 of a rifle bar 23 extending through the valve casing into the piston H for imparting rotation thereto in the usual manner. The ratchet ring 2!, valve bushing l9, and the valve casing it are held against relative rotation by any suitable means: such as dowel pin (not shown), and against lengthwise movement by a bearing plate 24 mounted on the ratchet ring 2! and clamped by a back head 25 which is secured to the cylinder 9 by two side bolts 26.

The valve cap I! is formed with a sleeved portion 2? extending partway into the casing Hi to form a bearing 28 for the lower end portion of' the valve 2!], and is provided with an annular groove 29 in constant communication with the rear end of the piston chamber Ill through a plurality of ports 38. Centrally through the valve cap il there is a bore 3! substantially larger than the diameter of the rifle bar 23, through which bore motive fluid may also be admitted into the rear end of the chamber it as will be explained later.

The valve 20, which is of a sleevelike shape, is provided intermediate its ends with an external annular flange 32 forming on the lower side thereof an actuating area 35-3 and on the other side an opposed actuating area 3d. Above the flange 32, the valve casing i8 is also shaped to form a valve bearing 35 above which is provided an annular groove 35 in constant communication with the front end of the cylinder Hi through one or more passages 59. Internally, the valve 26 bears on the bushing it which extends into the valve but falls short of the valve cap 51. Adjacent the annular groove 36, the valve bushing is formed with an annular shoulder 31 forming a valve seat for the upper end of the valve 20, which seat is provided with a plurality of ports 38 opening thereon between the marginal edges thereof and extending therefrom into the bushing iii in constant communication with radial ports 39 opening into inlet passages ll which passages extend from the bearing plate 24 into the valve cap I 7 through the ratchet ring 2! and valve casing l8. The lower end of the inlet ports (ill open into an annular groove M from where motive fluid may flow through radial ports t2 into longitudinally disposed ports 43 formed within the valve cap l'i between the ports and the bore 3!. The ports lZ-l are similar tothe ports 38 above described and lead to an annular valve seat Mi with which the lower end of the valve 29 is capable of engagement.

To lighten the valve 20, the same is provided with a central annular groove 4-5 extending into the annular flange 32. On one side of the groove 45, there is provided another annular groove 46 in communication with the upper end of the valve through a plurality of longitudinally disposed ports ll, which form with the groove 46 a motive fluid storing space, the purpose of which A will be explained later. Within the lower end portion of the valve there is provided an annular groove 48 in communication with the lower end of the valve through ports 49.

Opening into the chamber It, above the exhaust grooves M, there is a kick port 5i! leading to the valve actuating area 3A. This port near its opening into the chamber i ii is in communication with the atmosphere through a restricted vent 5!. Opening into the chamber H] below the ex- 55 and a radial port 55 capable of communication with a port 5'! provided within thehead 25 and opening into an enlarged annular groove 58 formed within the bearing plate 24.

In the operation, with the parts positioned as shown in Fig. 1, motive fluid from the throttle valve 54 is admitted into the enlarged annular groove 58 through the inlet passage 55 and the ports 56 and 51. From the groove 58 motive fluid is free to flow into the inlet ports and therefrom into the ports 38 provided within the valve bushing 19 through the radial ports 39. From the ports 40, the motive fluid will also be admitted 'into the annular groove M of the valve cap I1, and therefrom into the ports 43 via the radial ports 42, thereby admitting motive fluid directly on the two valve seats (Hand 44. When the valve 20 is engaging the lower valve seat 44, it is in spaced relation with the upper valve seat 21, thereby enabling a free flow of the fluid from the ports 38 into the annular groove 36, and therefrom into the lower endof the chamber I 0 through the passages 59. In this instance, the valve 20 is momentarily held stationary by the action of the fluid on the upper end of the valve adjacent the valve seat 3'7, which end forms a holding area for the valve. The pressure fluid admitted within the lower end of the chamber l9 through the passages 59 will act on the piston II to drive it upwardly. As the piston uncovers the kick port 52, the motive fluid from the chamber It] will flow to the actuating area 33 of the valve 20 via the kick port 52, and since this area is larger than the holding area adjacent the valve seat 31, the valve will shift into the position shown in Fig. 2, that is, into engagement with the valve seat 3'! for preventing supply of the motive fluid into the annular groove 35 and consequently into the lower end of the chamber l0.

By the time the valve 20 has assumed its new position, the piston ll driven upwardly by the motive fluid admitted into the front end of the chamber I0 will assume a position substantially as shown in Fig. 2, thereby enabling motive fluid from the front end of the piston chamber to exhaust to the atmosphere via the exhaust port I5. The valve 29 now engaging the valve seat \31 is in spaced relation with the valve seat 44, thereby enabling the motive fluidadmitted within ports 43 to flow into the annular groove 29 and therefrom into the rear end of the chamber 10 via the ports 30. From the ports 43 motive fluid may also flow into the rear end of the chamber l9 through the enlarged bore 3!. In

in openposition relative to the ports 39 and the bore 3| by the motive fluid acting on the lower end of the valve, which end forms a holding area similar to the upper end thereof. Due to the action of the motive fluid within the rear end or the chamber It], the piston ll will be driven downwardly to deliver its blow to the drill steel. During this downward movement of the piston, the motive fluid previously admitted on the valve actuating'area 33 will exhaust to the atmosphere via the kick port 52 and vent 53, thereby enabling the valve 20 to shift into the position shown in Fig. l. by the motive fluid admitted on the actuating area 34 via the kick port now uncovered by the piston ll. As the piston reaches the end of its forward stroke, it will uncover the exhaust grooves l4 to enable the motive fluid previously admitted into the rear end of the piston chamber to exhaust to the atmosphere via the exhaust port l5. 7

During the rearward stroke of the piston, the motive fluid previously admitted on the valve actuating area 34 will exhaust to the atmosphere through the kick port 59 and the vent 5|, thereby enabling the valve to shift to the position shown in Fig. 2 when the piston again uncovers the kick port 52.

In practice the valve ports 4'! and 49 having motive fluid constantly supplied therein by the inlet ports 38 and 43 respectively, actually constitute a reservoir for the motive fluid which has been found helpful to a quick discharge of motive fluid into both ends of the piston chamber, thereby enabling the stroke of the valve to be relatively small, that is, from .015" to .020". With reference to the admission of the motive fluid into the rear end of the piston chamber,

the combined area of the inlet ports 43 is cal-' culated to enable the supply of a relatively large amount of motive fluid into the rear end of the chamber l9 through the double inlet including the ports 39 and bore 3!. As shown in Fig. 2, it will be seen that from the inlet ports 43, the motive fluid may flow inside of the valve seat 44 to be supplied therefrom into the rear end of the chamber via the bore 31, and outside of the valve seat 44 into the chamber Ill via the ports 30, thereby enabling a quick and suflicient supply of motive fluid into the rear end of the piston chamber irrespective of the relatively small space between the lower end of the valve and its component valve seat 44.

Although the foregoing description is necessarily of a detailed character, in order to completely set forth the invention, it is to be understood that the specific terminology is not intended to be restrictive or confining and it is to be further understood that various rearrangements of parts and modifications of structural detail may be resorted to without departing from the scope or spirit of the invention as herein claimed.

I claim:

1. In a fluid actuated rock drill, a cylinder having a piston chamber and a piston reciprocable therein, an exhaust port for the piston chamher, a valve housing having opposed annular valve seats formed therein, a sleeve valve reciprocable within said housing between said seats, supplyports admitting motive fluid into said housing through said valve seats, spaces within said valve acting as constant storing means for motive fluid admitted into said housing through said valve seats, inlet passages leading from said housing to the piston chamber, an external annular flange on said valve having opposed actuating areas intermittently exposed to pressure fluid controlled by the piston for actuating the valve and causing the intermittent engagement of the ends of the 2. In a fluid actuated rock drill, a cylinder hav ing a piston chamber and a piston reciprocable therein, an exhaust port for the piston chamber, a valve housing having opposed annular valve seats formed therein, a sleeve valve reciprocable within said housing between said seats, supply ports admitting motive fluid into said housing through said valve seats, front inlet passages leading from said housing to one end portion of said chamber, rear inlet passages leading from said housing to the other end portion of said chamber and opening into said housing inside and outside of one of said annular valve seats, opposed actuating areas on said valve intermittently exposed to pressure fluid for effecting intermittent engagement of the valve with said seats to control communication between the supply ports and the inlet passages, and opposed holding areas on said valve exposed to pressure fluid flowing through said supply ports toward said areas and to said passages for momentarily holding the valve.

WILLIAM A. SMITH, JR. 

